1. Field of Invention
The present invention relates to a door latch, and more particularly to a powered latch assembly which is capable of converting a rotational driving force delivered by a power source, such as a motor or a solenoid, to a linear movement of a locking latch for locking a door of an enclosure, such as an oven door or sky lights etc.
2. Description of Related Arts
Conventional powered latch assemblies are widely utilized for locking a door, such as an oven door, to a main housing, such as an oven body, for a wide variety of purposes.
For instances, ovens are widely utilized domestically, commercially and industrially. Domestically, small or medium scale ovens are used to cook variety of food. Commercially, medium scale or large scale ovens are utilized to provide catering services. Industrially, large and heavy-duty ovens are utilized for such typically process as heat treatment.
Whatever kind of ovens are utilized, a typical oven usually comprises a main housing having a heating chamber formed therein, an oven door movably connected to the case for closing the reaction chamber, and a heat generating device disposed in the main housing for generating a substantial amount of heat inside the reaction chamber. Thus, it is extremely dangerous for leaving the oven door unlocked, especially when the oven is on or is in a dangerous condition because, say, the temperature inside the reaction chamber is still high notwithstanding that the oven is turned off.
Because of this, various locking devices (very often electrically powered) for ovens have been developed for locking the oven doors to the main housing so that no one can open the oven door when it is on or is still in a dangerous condition.
U.S. Pat. No. 6,315,336 of Swartzell discloses motorized self-cleaning oven latch in which the oven latch comprises a base, a pivot mounted on the base, a latch arm having a slot formed therein, the slot engaging the pivot and the latch arm sliding and rotating relative to the pivot, a motor, a cam rotatably driven by the motor from a first position to a second position, and a metal wire connected to the cam and the latch arm, the metal wire sliding and rotating the latch arm from an open position to a closed position as the cam rotates from the first position to the second position.
There are two major problems for this conventional art. First, no positive feedback is provided for indicating the door position. That means when the door is not fully closed with respect to the oven body, the oven latch has no way to know and subsequent attempt to lock up the door will fail, leaving the oven, and ultimately the user, being unaware the unsafe state of the oven door, in a dangerous condition.
Second, from the disclosed embodiments, one skill in the art would easily realize that the metal wire connecting the cam and the latch arm is an important element, any damages or distortions thereof invite total failure of the whole oven latch. Thus, it is of overriding important to keep the metal wire in question strong and durable in order to keep the oven latch in a good working condition. From the disclosed embodiments, no such features can reasonably be observed.
Several other types of latches have been developed. For example, U.S. Pat. No. 6,474,702 of Malone discloses a particular type of latch assemblies. As shown in the patent, that latch assembly employs pivotal movement of the latching arms for locking the oven door to the respective oven body. The pivotal movement of the latching arms is driven by a motor through some sorts of pivotal transmission arrangements. Those transmission arrangements are typically complicated in structure and numerous in components involved so that the possibility of getting defective is higher, in that failure of any one of those numerous components would lead to failure of the whole latch assembly.